gcc-func.c

使用yacc和lex编写的cmm语言的词法分析和语法分析程序.

tree convert (type, expr)
     tree type, expr;
{
  register tree e = expr;
  register enum tree_code code = TREE_CODE (type);

  if (type == TREE_TYPE (expr) || TREE_CODE (expr) == ERROR_MARK)
    return expr;
  if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
    return error_mark_node;
  if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }
  if (code == VOID_TYPE)
    return build1 (CONVERT_EXPR, type, e);
#if 0
  /* This is incorrect.  A truncation can't be stripped this way.
     Extensions will be stripped by the use of get_unwidened.  */
  if (TREE_CODE (expr) == NOP_EXPR)
    return convert (type, TREE_OPERAND (expr, 0));
#endif
  if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
    return fold (convert_to_integer (type, e));
  if (code == POINTER_TYPE)
    return fold (convert_to_pointer (type, e));
  if (code == REAL_TYPE)
    return fold (convert_to_real (type, e));

  error ("conversion to non-scalar type requested");
  return error_mark_node;
}

tree default_conversion (exp)
     tree exp;
{
  register tree type = TREE_TYPE (exp);
  register enum tree_code code = TREE_CODE (type);

  /* Constants can be used directly unless they're not loadable.  */
  if (TREE_CODE (exp) == CONST_DECL)
    exp = DECL_INITIAL (exp);
  /* Replace a nonvolatile const static variable with its value.  */
  else if (optimize
	   && TREE_CODE (exp) == VAR_DECL
	   && TREE_READONLY (exp)
	   && DECL_MODE (exp) != BLKmode)
    {
      exp = decl_constant_value (exp);
      type = TREE_TYPE (exp);
    }

  /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
  if (TREE_CODE (exp) == NON_LVALUE_EXPR)
    exp = TREE_OPERAND (exp, 0);

  /* Normally convert enums to int,
     but convert wide enums to something wider.  */
  if (code == ENUMERAL_TYPE)
    {
      type = type_for_size (MAX (TYPE_PRECISION (type),
				 TYPE_PRECISION (integer_type_node)),
			    (flag_traditional && TREE_UNSIGNED (type)));
      return convert (type, exp);
    }

  if (code == INTEGER_TYPE
      && (TYPE_PRECISION (type)
	  < TYPE_PRECISION (integer_type_node)))
    {
      /* Traditionally, unsignedness is preserved in default promotions.  */
      if (flag_traditional && TREE_UNSIGNED (type))
	return convert (unsigned_type_node, exp);
      return convert (integer_type_node, exp);
    }
  if (flag_traditional && type == float_type_node)
    return convert (double_type_node, exp);
  if (code == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }
  if (code == FUNCTION_TYPE)
    {
      return build_unary_op (ADDR_EXPR, exp, 0);
    }
  if (code == ARRAY_TYPE)
    {
      register tree adr;
      tree restype = TREE_TYPE (type);
      tree ptrtype;

      if (TREE_CODE (exp) == INDIRECT_REF)
	return convert (TYPE_POINTER_TO (restype),
			TREE_OPERAND (exp, 0));

      if (TREE_CODE (exp) == COMPOUND_EXPR)
	{
	  tree op1 = default_conversion (TREE_OPERAND (exp, 1));
	  return build (COMPOUND_EXPR, TREE_TYPE (op1),
			TREE_OPERAND (exp, 0), op1);
	}

      if (!lvalue_p (exp)
	  && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
	{
	  error ("invalid use of non-lvalue array");
	  return error_mark_node;
	}

      if (TYPE_READONLY (type) || TYPE_VOLATILE (type))
	restype = c_build_type_variant (restype, TYPE_READONLY (type),
					TYPE_VOLATILE (type));

      ptrtype = build_pointer_type (restype);

      if (TREE_CODE (exp) == VAR_DECL)
	{
	  /* ??? This is not really quite correct
	     in that the type of the operand of ADDR_EXPR
	     is not the target type of the type of the ADDR_EXPR itself.
	     Question is, can this lossage be avoided?  */
	  adr = build1 (ADDR_EXPR, ptrtype, exp);
	  if (mark_addressable (exp) == 0)
	    return error_mark_node;
	  TREE_CONSTANT (adr) = staticp (exp);
	  TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
	  return adr;
	}
      /* This way is better for a COMPONENT_REF since it can
	 simplify the offset for a component.  */
      adr = build_unary_op (ADDR_EXPR, exp, 1);
      return convert (ptrtype, adr);
    }
  return exp;
}

/* Make an expression to refer to the COMPONENT field of
   structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */

tree
build_component_ref (datum, component)
     tree datum, component;
{
  register tree type = TREE_TYPE (datum);
  register enum tree_code code = TREE_CODE (type);
  register tree field = NULL;
  register tree ref;

  /* If DATUM is a COMPOUND_EXPR or COND_EXPR, move our reference inside it
     unless we are not to support things not strictly ANSI.  */
  switch (TREE_CODE (datum))
    {
    case COMPOUND_EXPR:
      {
	tree value = build_component_ref (TREE_OPERAND (datum, 1), component);
	pedantic_lvalue_warning (COMPOUND_EXPR);
	return build (COMPOUND_EXPR, TREE_TYPE (value),
		      TREE_OPERAND (datum, 0), value);
      }
    case COND_EXPR:
      pedantic_lvalue_warning (COND_EXPR);
      return build_conditional_expr
	(TREE_OPERAND (datum, 0),
	 build_component_ref (TREE_OPERAND (datum, 1), component),
	 build_component_ref (TREE_OPERAND (datum, 2), component));
    }

  /* See if there is a field or component with name COMPONENT.  */

  if (code == RECORD_TYPE || code == UNION_TYPE)
    {
      if (TYPE_SIZE (type) == 0)
	{
	  incomplete_type_error (0, type);
	  return error_mark_node;
	}

      /* Look up component name in the structure type definition.

	 If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
	 to the field elements.  Use a binary search on this array to quickly
	 find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
	 will always be set for structures which have many elements.  */

      if (TYPE_LANG_SPECIFIC (type))
	{
	  int bot, top, half;
	  tree *field_array = &TYPE_LANG_SPECIFIC (type)->elts[0];

	  field = TYPE_FIELDS (type);
	  bot = 0;
	  top = TYPE_LANG_SPECIFIC (type)->len;
	  while (top - bot > 1)
	    {
	      int cmp;

	      half = (top - bot + 1) >> 1;
	      field = field_array[bot+half];
	      cmp = (long)DECL_NAME (field) - (long)component;
	      if (cmp == 0)
		break;
	      if (cmp < 0)
		bot += half;
	      else
		top = bot + half;
	    }

	  if (DECL_NAME (field_array[bot]) == component)
	    field = field_array[bot];
	  else if (DECL_NAME (field) != component)
	    field = 0;
	}
      else
	{
	  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
	    {
	      if (DECL_NAME (field) == component)
		break;
	    }
	}

      if (!field)
	{
	  error (code == RECORD_TYPE
		 ? "structure has no member named `%s'"
		 : "union has no member named `%s'",
		 IDENTIFIER_POINTER (component));
	  return error_mark_node;
	}
      if (TREE_TYPE (field) == error_mark_node)
	return error_mark_node;

      ref = build (COMPONENT_REF, TREE_TYPE (field), datum, field);

      if (TREE_READONLY (datum) || TREE_READONLY (field))
	TREE_READONLY (ref) = 1;
      if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (field))
	TREE_THIS_VOLATILE (ref) = 1;

      return ref;
    }
  else if (code != ERROR_MARK)
    error ("request for member `%s' in something not a structure or union",
	    IDENTIFIER_POINTER (component));

  return error_mark_node;
}

tree build_unary_op (code, xarg, noconvert)
     enum tree_code code;
     tree xarg;
     int noconvert;
{
  /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
  register tree arg = xarg;
  register tree argtype = 0;
  register enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
  char *errstring = NULL;
  tree val;

  if (typecode == ERROR_MARK)
    return error_mark_node;
  if (typecode == ENUMERAL_TYPE)
    typecode = INTEGER_TYPE;

  switch (code)
    {
    case CONVERT_EXPR:
      /* This is used for unary plus, because a CONVERT_EXPR
	 is enough to prevent anybody from looking inside for
	 associativity, but won't generate any code.  */
      if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
        errstring = "wrong type argument to unary plus";
      else if (!noconvert)
	arg = default_conversion (arg);
      break;